Now that I have most of my flooring and walls in place, I have a much better picture of the space I have to work with. While I really like my original idea for a combination bookcase and folding spiral staircase, I realized that it would not work out in the space I have. Here is another option though- it still fulfills my goals of being space efficient and multi-purpose. It will look like a normal book case against the wall just under the edge of my loft. When I need stairs, it will pivot against the bottom shelf and the top will pull out against the edge of the loft. I will install pulleys with a counter weight (similar to a sash window) so it will not slam open. The construction should be fairly straight forward with this one. I will make each shelf/step out of wood, with some sort of bearing or low friction slide on the top. A set of steel slides will hold the unit together and keep each step plumb as they slide.